Optics for controlling light transmitted through a conical quartz dome

ABSTRACT

Embodiments described herein generally relate to apparatus for heating substrates. The apparatus generally include a process chamber having a substrate support therein. A plurality of lamps is positioned to provide radiant energy through an optically transparent dome to a substrate positioned on the substrate support. A light focusing assembly is positioned within the chamber to influence heating and temperature distribution on the substrate and to facilitate formation of a film on a substrate having uniform properties, such as density. The light focusing assembly can include one or more reflectors, light pipes, or refractive lenses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/785,539, filed Mar. 5, 2013, which claimsbenefit of U.S. Provisional Patent Application Ser. No. 61/637,998,filed Apr. 25, 2012, and U.S. Provisional Patent Application Ser. No.61/662,166, filed Jun. 20, 2012. The aforementioned applications areherein incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the present invention generally relate to apparatus forheating substrates, such as semiconductor substrates.

Description of the Related Art

Semiconductor substrates are processed for a wide variety ofapplications, including the fabrication of integrated devices andmicrodevices. One method of processing substrates includes depositing amaterial, such as a dielectric material or a conductive metal, on anupper surface of the substrate. The material may be deposited in alateral flow chamber by flowing a process gas parallel to the surface ofa substrate positioned on a support, and thermally decomposing theprocess gas to deposit a material from the gas onto the substratesurface. Because a heated substrate facilitates the thermaldecomposition of the process gas, it is desirable to have a uniformsubstrate temperature in order to effect a uniform deposition on thesubstrate. Non-uniformities in the temperature of the substrate canresult in a non-uniform material deposition on the substrate, whichultimately affects the performance of the final manufactured device.

Therefore, there is a need for an apparatus for uniformly heating asubstrate.

SUMMARY OF THE INVENTION

Embodiments described herein generally relate to apparatus for heatingsubstrates. The apparatus generally include a process chamber having asubstrate support therein. A plurality of lamps is positioned to provideradiant energy through an optically transparent dome to a substratepositioned on the substrate support. A light focusing assembly ispositioned within the chamber to influence heating and temperaturedistribution on the substrate and to facilitate formation of a film on asubstrate having uniform properties, such as density. The light focusingassembly can include one or more reflectors, light pipes, or refractivelenses.

In one embodiment, a process chamber comprises a chamber body includingan optically transparent dome. A substrate support is disposed withinthe chamber body. A plurality of lamps is disposed adjacent to theoptically transparent dome. A light focusing assembly is positionedwithin the chamber body between the plurality of lamps and a substratepositioned on the substrate support. The light focusing assembly isadapted to influence radiant energy emitted from the plurality of lamps.

In another embodiment, a process chamber comprises a chamber bodyincluding an optically transparent dome. A substrate support is disposedwithin the chamber body. The substrate support has a support shaft witha hollow cavity therein extending therefrom. A plurality of lamps isdisposed adjacent to the optically transparent dome. A light focusingassembly is positioned within the chamber body between the opticallytransparent dome and the substrate support. The light focusing assemblyis in contact with an upper surface of the optically transparent domeand is adapted to influence radiant energy emitted from the plurality oflamps.

In another embodiment, an optical assembly comprises a plurality ofconcentric rings formed from an optically transparent material. Eachconcentric ring has a hollow cavity therein. A reflective material isdisposed within the hollow cavities of the concentric rings, and aplurality of refractive elements couple adjacent concentric rings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic sectional view of a processing chamber accordingto one embodiment of the invention.

FIGS. 2A and 2B are schematic illustrations of a light focusing assemblyaccording to one embodiment of the invention.

FIGS. 3A-3D are schematic illustrations of light focusing assembliesaccording to other embodiments of the invention.

FIG. 4 illustrates a light focusing assembly according to anotherembodiment of the invention.

FIG. 5 illustrates a light focusing assembly according to anotherembodiment of the invention.

FIG. 6 illustrates a light focusing assembly according to anotherembodiment of the invention.

FIG. 7 illustrates a light focusing assembly according to anotherembodiment of the invention.

FIGS. 8A and 8B are perspective views of a ring according to oneembodiment of the invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments described herein generally relate to apparatus for heatingsubstrates. The apparatus generally include a process chamber having asubstrate support therein. A plurality of lamps is positioned to provideradiant energy through an optically transparent dome to a substratepositioned on the substrate support. A light focusing assembly ispositioned between the optically transparent dome and the substratesupport to influence heating and temperature distribution on thesubstrate and to facilitate formation of a film on a substrate havinguniform properties, such as density. The light focusing assembly caninclude one or more reflectors, light pipes, or refractive lenses.

FIG. 1 is a schematic sectional view of a processing chamber 100according to one embodiment of the invention. The processing chamber 100may be used to process one or more substrates, including the depositionof a material on an upper surface of a substrate. The processing chamber100 includes a chamber body 101, an upper dome 102 formed from amaterial such as a stainless steel, aluminum, ceramics (e.g., quartz),or coated metals or ceramics. The processing chamber 100 also includes alower dome 104 formed from an optically transparent material such asquartz. The lower dome 104 is coupled to, or is an integral part of, thechamber body 101. A substrate support 106 adapted to support a substrate108 thereon is disposed within the processing chamber 100 between theupper dome 102 and the lower dome 104. The substrate support 106 iscoupled to a support plate 109 and forms a gap 111 therebetween. Thesupport plate 109 is be formed from an optically transparent material,such as quartz, to allow radiant energy from lamps 142 to impinge uponand heat the substrate support 106 to a desired processing temperature.The substrate support 106 is formed from silicon carbide or graphitecoated in silicon carbide to absorb radiant energy from the lamps 142and conduct the radiant energy to the substrate 108.

The substrate support 106 is shown in an elevated processing position,but may be vertically actuated by an actuator 112 to a loading positionbelow the processing position to allow lift pins 110 to contact thelower dome 104 and raise the substrate 108 from the substrate support106. A robot (not shown) may then enter the processing chamber 100 toengage and remove the substrate 108 therefrom through an opening 114,such as a slit valve. The substrate support 106 is also adapted to berotated during processing by the actuator 112 to facilitate uniformprocessing of the substrate 108.

The substrate support 106, while located in the processing position,divides the internal volume of the processing chamber 100 into a processgas region 116 and a purge gas region 118. The process gas region 116includes the internal chamber volume located between the upper dome 102and a plane 120 of the substrate support 106 while the substrate support106 is located in the processing position. The purge gas region 118includes the internal chamber volume located between the lower dome 104and the plane 120.

Purge gas supplied from a purge gas source 122 is introduced to thepurge gas region 118 through a purge gas inlet 124 formed within asidewall of the chamber body 101. The purge gas flows laterally alongflow path 126 across the back surface of the support 106, and isexhausted from the purge gas region 118 through a purge gas outlet 128located on the opposite side of the processing chamber 100 as the purgegas inlet 124. An exhaust pump 130, coupled to the purge gas outlet 128,facilitates removal of the purge gas from the purge gas region 118.

Process gas supplied from a process gas supply source 132 is introducedinto the process gas region 116 through a process gas inlet 134 formedin a sidewall of the chamber body 101. The process gas flows laterallyacross the upper surface of the substrate 108 along flow path 136. Theprocess gas exits the process gas region 116 through a process gasoutlet 138 located on the opposite side of the processing chamber 100 asthe process gas inlet 134. Removal of the process gas through theprocess gas outlet 138 is facilitated by a vacuum pump 140 coupledthereto.

A plurality of lamps 142 are disposed adjacent to and beneath the lowerdome 104 to heat the substrate 108 as the process gas passes thereoverto facilitate the deposition of a material onto the upper surface of thesubstrate 108. The lamps include bulbs 141 surrounded by an optionalreflector 143. Each lamp 142 is coupled to a power distribution board147 through which power is supplied to each lamp 142. The lamps 142 arearranged in annular groups of increasing radius around a shaft 127 ofthe substrate support 106. The shaft 127 is formed form quartz andcontains a hollow portion or cavity 129 therein, which reduces lateraldisplacement of radiant energy near the center of the substrate 108,thus facilitating uniform irradiation of the substrate 108.

The lamps 142 are adapted to the heat the substrate to a predeterminedtemperature to facilitate thermal decomposition of the process gas ontothe surface of the substrate 108. In one example, the material depositedonto the substrate may be a group III, group IV, and/or group Vmaterial, or may be a material including a group III, group IV, and/orgroup V dopant. For example, the deposited material may include galliumarsenide, gallium nitride, or aluminum gallium nitride. The lamps may beadapted to heat the substrate to a temperature within a range of about300 degrees Celsius to about 1200 degrees Celsius, such as about 300degrees Celsius to about 950 degrees Celsius. Radiant energy from thelamps 142 is directed to the substrate support 106 by a light focusingassembly 150 to controllably heat the substrate 108, thus resulting in amore uniform deposition on the substrate 108. The uniform deposition onthe substrate 108 results in a higher quality substrate and a moreefficient manufactured device. The light focusing assembly 150 ispositioned above and in contact with the lower dome 104, adjacent to thepurge gas region 118. Thus, the light focusing assembly 150 is locatedwithin an internal volume of the processing chamber 100.

One or more lamps 142 are positioned within a lamphead 145 which may becooled during or after processing by a cooling fluid introduced intochannels 149 located between the lamps 142. The lamphead 145conductively cools the lower dome 104 due in part to the close proximityof the lamphead 145 to the lower dome 104. The lamphead 145 also coolsthe lamp walls and walls of the reflectors 143 as well.

Although FIG. 1 illustrates one embodiment of a processing chamber,additional embodiments are also contemplated. For example, in anotherembodiment, it is contemplated that the substrate support 106 may beformed from an optically transparent material, such as quartz, to allowfor direct heating of the substrate 108. In yet another embodiment, itis contemplated that an optional circular shield 139 may be disposedaround the substrate support 106 and coupled to a sidewall of thechamber body 101. In another embodiment, the process gas supply source132 may be adapted to supply multiple types of process gases, forexample, a group III precursor gas and a group V precursor gas. Themultiple process gases may be introduced into the chamber through thesame process gas inlet 134, or through different process gas inlets 134.Additionally, it is also contemplated that the size, width, and/ornumber of gas inlets 124, 134, or gas outlets 128, 138 may be adjustedto further facilitate a uniform deposition of material on the substrate108. In yet another embodiment, it is contemplated that the lampheads145 are not in contact with the lower dome 104. In another embodiment,the substrate support 106 may be an annular ring or edge ring having acentral opening therethrough, and may be adapted to support theperimeter of the substrate 108. In such an embodiment, the substratesupport 106 may be formed from silicon carbide, silicon-carbide-coatedgraphite, or glassy-carbon-coated graphite.

FIGS. 2A and 2B are schematic illustrations of the light focusingassembly 250 according to one embodiment of the invention. FIG. 2Aillustrates a perspective view of the light focusing assembly 250. FIG.2B illustrates a sectional view of the light focusing assembly 250 alongthe section line 2B-2B. The light focusing assembly 250 is similar toand may be used in place of the light focusing assembly 150. The lightfocusing assembly 250 includes a plurality of concentric rings 251A-251Fof increasing diameter. The rings 251A-251F are adapted to increaselight collimation, homogenization, and/or substrate illuminationuniformity. The centermost ring 251A includes an opening 252 therein toaccommodate a support shaft of a substrate support. A gap 253 isdisposed between adjacent vertical surfaces of each of the rings251A-251F to allow radiant energy from heat lamps to pass between therings 251A-251F and heat a substrate during processing. Generally, eachgap 253 corresponds to one ring or zone of lamps within a processchamber. It is to be noted that the size and number of gaps 253 can beadjusted depending on the size and number of lamps utilized within aprocess chamber.

The rings 251A-251F are hollow rings or dewars formed from quartz orother optically transparent material and have a reflective materialdisposed on internal surfaces 260 of a hollow cavity formed therein. Forexample, the internal surfaces 260 may have an aluminum, silver, gold orother reflective coating thereon to reflect radiant energy such as lighttowards a substrate in a predetermined manner to facilitate uniformheating of a substrate. Placement of the reflective material within therings 251A-251F protects the reflective material from cleaning gasesutilized during cleaning processes. The rings 251A-251F have two outervertical surfaces 254, each or which are parallel to one another, and atop surface 255 which is perpendicular to the vertical surfaces 254. Thetop surface 255 is generally positioned parallel to a substrate within aprocess chamber. A bottom surface 256 of each ring 251A-251F ispositioned at an angle with respect to the upper surface 255. The angleof the bottom surfaces 256 is selected to match the angle of a lowerdome within a process chamber to facilitate contact between the bottomsurfaces 256 and a lower dome. It is to be noted that the top surfaces255 of the two innermost rings 251A and 251B are disposed below theplane of the top surfaces 255 of the remaining rings 251C-251F. It isbelieved that the reduced height of the innermost rings 251A and 251Bfacilitates more uniform heating of the substrate by providing a moreuniform irradiation of the center of the substrate support and/orsubstrate. However, it is contemplated that the upper surfaces of rings251A and 251B may be coplanar with the upper surfaces of rings 251C-251Fin some embodiments.

The rings 251A-251F may have a thickness within a range from about 2.5millimeters to about 35 millimeters, for example, about 2.5 millimetersto about 5 millimeters, or about 25 millimeters to about 35 millimeters.In one example, the rings 251A-251F may have walls with a thickness ofabout 1 millimeter each. In such an example, the rings 251A-251F mayhave cavities therein with a width of about 0.5 millimeters to about 33millimeters, such as about 0.5 millimeters to about 3 millimeters, orabout 23 millimeters to about 33 millimeters. In embodiments where thecavity has a width greater than about 5 millimeters, the upper surfaceof the cavity may also be coated with a reflective material. Thereflective material on the upper surface of the cavity reflects anyradiant energy not absorbed by the substrate support 106 back towardsthe substrate support 106, thus enhancing process efficiency.Additionally, as the width of each of the rings 251A-251F increases, thegap 253 therebetween decreases. The decreasing gap size reduces theamount of radiant energy that can reenter the gaps 253 (e.g., bydownward reflection from a substrate or substrate support, or by directthermal radiation from the substrate or substrate support) by reducingthe angle at which light is permitted to enter the gap 253. Such radiantenergy which enters the gap 253 may reduce process efficiency.

As shown in FIG. 2B, the light focusing assembly 250 generally has aconical cross-section, with the height of each ring increasing as theradii of the rings decrease. However, as noted above, in someembodiments, the inner most rings 251A and optionally 251B may havereduced height in order to promote uniform irradiation near the centerof a substrate support. In another embodiment, it is contemplated thetop surfaces of rings 251A-251F may all be coplanar. In such anembodiment, the innermost ring 251A would have the greatest height.

FIGS. 2A and 2B illustrates one embodiment of light focusing assembly,however, other embodiments are also contemplated. In another embodiment,it is contemplated that the rings 251A-251F may be solid, and thereflective material may be disposed on the outside of the rings251A-251F. In such an embodiment, the reflective material may be coveredwith a protective dielectric coating, such as silicon dioxide, toprotect the reflective material from corrosive cleaning gases. In yetanother embodiment, it is contemplated that the internal surfaces 260 ofthe rings 251A-251F may not be covered in a reflective material.Instead, a reflective element, such as aluminum foil, may be positionedwithin the cavity formed within each of the rings 251A-251F. In yetanother embodiment, it is contemplated that one or both of the verticalsurfaces 254 or internal surfaces 260 may be disposed at an angle thetawith respect to the Z axis. The angle theta may be within a range fromabout −20 degrees to about 20 degrees, and need not be the same for eachof the vertical surfaces 254 or internal surface 260.

FIGS. 3A-3D are schematic illustrations of light focusing assembliesaccording to other embodiments of the invention. FIG. 3A illustrates atop perspective view of a light focusing assembly 350. The lightfocusing assembly 350 is similar to the light focusing assembly 250,except that the light focusing assembly 350 includes refractive elements360 coupled to the lower portions of rings 251A-251F. The refractiveelements 360 are convex, concave, linear, Fresnel, or other lenses,formed from an optically transparent material such as quartz. Therefractive elements 360, in combination with the reflective propertiesof the rings 251A-251F, are adapted to increase light collimation,homogenization, and/or substrate illumination uniformity. The lowersurfaces of each of the refractive elements 360 is linear and coplanarwith the lower surfaces 256 of the rings 251A-251F, thus facilitatingmating of the light focusing assembly 350 to a lower dome in a processchamber.

FIG. 3B illustrates a sectional view of the light focusing assembly 350along the section line 3B-3B. The refractive elements 360 are coupled tothe lower vertical edges of the rings 251A-251F, and couple the rings251A-251F to one another, thus increasing the rigidity of the lightfocusing assembly 350. In another embodiment, it is contemplated thatthe refractive elements 360 may form a conical unitary piece similar insize and shape to a lower dome of a process chamber. In such anembodiment, the rings are coupled to the upper surface of the unitarypiece, which can then be positioned on or above the lower dome of aprocess chamber. In yet another embodiment, it is contemplated that therefractive elements may be coupled directly to a lower dome within aprocess chamber, or formed as an integral part of a lower dome. Inanother embodiment, it is contemplated that the refractive elements 360may be separate and individually replaceable.

FIG. 3C illustrates an enlarged schematic view of a portion of the lightfocusing assembly 350 according to one embodiment. FIG. 3C illustrates arefractive element 360A positioned between and in contact with rings251A and 251B. The refractive element 360A is a convex lens whichfacilitates collimation and homogenization of radiant energy emittedfrom lamps positioned proximate to the refractive element 360A. Therefractive element 360A is shown having a convex shape; however, othershapes, including concave or linear, are also contemplated.

FIG. 3D illustrates an enlarged schematic view of a portion of the lightfocusing assembly 350 according to another embodiment. The refractiveelement 360B illustrated in FIG. 3D is a Fresnel lens, which reduces theamount or material required to form the lens compared to a conventionallens, such as the refractive element 360A illustrated in FIG. 3C. Theuse of the refractive element 360B reduces the weight of the lightfocusing assembly 350. The refractive element 360A includes a pluralityof concentric annular sections 361, or Fresnel zones, surrounding aconvex lens 362. It is to be noted that the design of the refractiveelement 360B is exemplary, and other lens designs are contemplated, suchas diffusive optics.

In another embodiment, it is contemplated that the refractive elements360A and/or 360B may be coupled to the support plate 109 of FIG. 1, andthus are actuated with the substrate support 106. In such an embodiment,the light focusing assembly 350 may be excluded, thereby simplifying thedesign of the processing chamber 100 and reducing the production cost ofprocessing chamber 100. Furthermore, since the light focusing assembly350 could be excluded, the thickness of the lower dome 104 could bereduced since the lower dome 104 would no longer need to provide supportfor the light focusing assembly 350. The decrease in thickness of thelower dome 104 further reduces manufacturing costs. In yet anotherembodiment, it is contemplated that the refractive elements 360A and/or360B may be positioned on the lower dome 104, and the concentric rings251A-251F may be excluded. In such an embodiment, the absence of theconcentric rings results in reduced production costs.

FIG. 4 illustrates a light focusing assembly 450 according to anotherembodiment of the invention. The light focusing assembly 450 includesconcentric rings 451A-451F disposed between and coupled to an opticallytransparent lower plate 404 and an optically transparent upper plate474. The optically transparent lower plate 404 is sized and shaped to bepositioned on a lower dome, such as the lower dome 104 shown in FIG. 1.The optically transparent lower plate 404 may be coupled to the lowerdome 104 by an adhesive or by interlocking pieces. The opticallytransparent upper plate 474 is coupled to the concentric rings 451A-451Fopposite the optically transparent lower plate 404. The concentric rings451A-451F, the optically transparent lower plate 404, and the opticallytransparent upper plate 474 may be machined from a unitary block ofmaterial, such as quartz, or may be constructed individually and thenassembled. The concentric rings 451A-451F, the lower dome 104, and theoptically transparent upper plate 474 are positioned to form gaps 475between each of the concentric rings 451A-451F. The gaps 475 arepositioned over lamps within a processing chamber, such as processingchamber 100 shown in FIG. 1. The gaps 475 are generally evacuated toform a vacuum therein.

The internal surfaces 460 of each gap 475 (e.g., the surfaces of theconcentric rings 451A-451F) are coated with a reflective material toenhance illumination control. Thus, a hollow cavity within eachconcentric ring 451A-451F need not be formed and coated. Such anembodiment simplifies production and repair of reflectively-coatedsurfaces. Because each gap 475 is a sealed enclosure, the reflectivematerial therein is protected from process and cleaning gases.

The surfaces 460 of the concentric rings 451A-451F may be coated byforming an opening within the optically transparent lower plate 404 orthe optically transparent upper plate 474, and introducing a reflectivematerial, such as a liquid which is subsequently dried, into each gap475. Undesired reflective material may be removed, for example, byetching. Additionally or alternatively, the undesired deposition ofreflective material can be reduced or prevented by masking surfaces uponwhich deposition is not desired. In yet another embodiment, for example,when constructing the light focusing assembly 450 from individualcomponents, the reflective material may be deposited on the surfaces 460prior to assembly. In such an embodiment, deposition, masking, and/oretching may be simplified. It should be noted that application ofreflective material to the concentric rings 251A-251F (shown in FIGS.2A, 2B, 3A, and 3B) may be performed in a similar manner.

FIG. 4 illustrates one embodiment of a light focusing assembly 450,although other embodiments are also contemplated. For example, it iscontemplated that the concentric rings 451A-451F may be formed from ametal or other reflective material, rather than an optically transparentmaterial coated with a reflective material. For example, the concentricrings 451A-451F may be formed from silver, gold, copper, aluminum, orcombinations thereof. In some instances, the fabrication of the theconcentric rings 451A-451F form a metal rather than quartz may requireless manufacturing steps and may reduce manufacturing costs.Additionally, repair and replacement of the concentric rings 451A-451Fmay be simplified.

FIG. 5 illustrates a light focusing assembly 550 according to anotherembodiment of the invention. The light focusing assembly 550 is similarto the light focusing assembly 450; however, the optically transparentupper plate 474 does not contact all of the concentric rings 451A-451Fdue to the spaces 570. Thus, the gaps 575 are in fluid communication.Such an embodiment simplifies evacuation of the gap 575, as well asapplication of reflective material. Additionally, the spaces 570 providea break in the thermal conduction path between the optically transparentlower plate 404 and the optically transparent upper plate 474, therebyreducing the conductive heat flow from the upper plate 474 to the lowerplate 404 and consequently the lower chamber done 104 (shown in FIG. 1).Because excess heat is removed from the optically transparent lowerplate 404 and the lower chamber dome 104 via cooling channels disposedin the lampheads 145 (shown in FIG. 1) as discussed above, the reductionin conductive heat flow results in either reduced lower dometemperatures, or if the lower dome temperature is required to have aminimum value, a reduced coolant flow in the lamphead.

FIG. 5 illustrates one embodiment of a light focusing assembly 550, butother embodiments are also contemplated. For example, it is contemplatedthat the optically transparent upper plate 474 may contact some or allof the concentric rings 551A-551E at discrete points via extension ofthe concentric rings 551A-551E. Contact between the concentric rings551A-551E and the optically transparent upper plate 474 increases thestructural rigidity of the light focusing assembly 550. In such anembodiment, some spaces 570 remain so as to maintain the fluidcommunication of the gaps 575. In another embodiment, it is contemplatedthat cross rods formed from an optically transparent material may bepositioned between adjacent concentric rings 551A-551F to increase thestructural rigidity of the light focusing assembly 550.

FIG. 6 illustrates a light focusing assembly 650 according to anotherembodiment of the invention. The light focusing assembly 650 includes aplurality of concentric rings 651A-651C. While three concentric ringsare shown, it is contemplated that more or less concentric rings may beincludes, for example, one concentric ring per ring of lamps in aprocessing chamber. The concentric rings 651A-651C are formed from anoptically transparent material, such as quartz, and are positioned overlamps 142. In such an embodiment, the concentric rings 651A-651Cfunction as refractive elements to influence irradiance from the lamps142 and to facilitate uniform processing of substrates. The concentricrings 651A-651C reduce the diffusion of the light from the lamps 142,thereby reducing the cross-coupling of irradiation from lamps 142 on asubstrate, particularly between radial arrays of lamps.

FIG. 7 illustrates a light focusing assembly 750 according to anotherembodiment of the invention. The light focusing assembly 750 is similarto the light focusing assembly 650, except the light focusing assemblyincludes concentric rings 751B and 751C which are polygonalapproximations of concentric rings. The concentric rings 751B and 751Care composed of discrete polygons 779 which are sized, shaped, andassembled to approximate a ring. Each concentric ring 751B and 751C iscomposed of multiple polygons 779, and it is contemplated that thenumber of polygons 779 in each ring may be more or less than is shown.The use of polygons 779, rather than perfect rings, increases the mixingof light from the lamps 142 resulting in a more reproducible irradiationprofile by rendering the resultant irradiation profile less dependent onindividual lamp characteristics. In some instances, the use of polygons779 may improve the distribution profile of the lamps 142.

Each ring need not include the same number of polygons 779, and thus,not the same number of facets. Additionally, while the polygons 779 areillustrates as being disposed over one or two lamps 142, it iscontemplated that each polygon 779 may be positioned over any numberlamps 142. It is contemplated that adjacent polygons 779 may be incontact, or a gap may be positioned therebetween to increase the totalinternal reflection by the creation of the additional surfaces. Theadjacent surfaces of adjacent polygons 779 may be transparent, or may becoated with a reflective material.

FIGS. 8A and 8B illustrate perspective views of a ring 851 according toone embodiment of the invention. The ring 851 may be utilized in any ofthe embodiments described herein, for example, as a ring 251A, 451A,651A or 751A. The ring 851 includes a first face 890 which is circular,and a second face 891 which is polygonal. The ring 851 includes anopening disposed centrally therethrough. The number of polygonal facetsmay be adjusted to facilitate the desired amount of light mixing. It iscontemplated that the surfaces of each of the first face 890 and thesecond face 891 may be shaped to include specific refractive elementsthereon, such as concave or convex lenses. The sidewalls of the ring 851connecting the first face 890 and the second face 890 are generallyparallel, however, non-parallel embodiments are also contemplated. Thering 851 may be positioned within a process chamber wither either thefirst face 809 or the second face 891 positioned towards one or morelamps.

While numerous reflective and refractive elements are described herein,it is contemplated that any of the reflective or refractive elements maybe utilized alone or in combination with one another.

Benefits of the present invention include increased collimation andhomogenization of radiant energy within a process chamber. The increasedcollimation and homogenization result in more controlled heating ofsubstrates, which in turn, results in a more uniform deposition profileand material properties on the substrates. The uniform depositionprofile on the substrates results in high quality and more efficientmanufactured devices.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A process chamber, comprising: a chamber body including a dome thatallows transmission of radiant energy therethrough; a substrate supportdisposed within the chamber body; a plurality of lamps disposed adjacentto the dome; and a light focusing assembly positioned within the chamberbody between the plurality of lamps and the substrate support, wherein:the light focusing assembly comprises a plurality of concentric rings orpolygonal approximations to rings, the concentric rings or the polygonalapproximations to rings having gaps therebetween and comprising amaterial that allows transmission of radiant energy therethrough; andthe concentric rings or the polygonal approximations to rings include areflective coating on sidewalls thereof adjacent the gaps.
 2. Theprocess chamber of claim 1, further comprising a lower plate and anupper plate disposed at respective ends of the plurality of concentricrings or polygonal approximations to rings.
 3. The process chamber ofclaim 2, wherein the reflective coating comprises gold or aluminum. 4.The process chamber of claim 2, wherein the reflective coating comprisessilver.
 5. The process chamber of claim 1, wherein at least some of theconcentric rings have different heights.
 6. The process chamber of claim1, wherein the material that allows the transmission of radiant energytherethrough comprises quartz.
 7. The process chamber of claim 1,wherein the concentric rings each have a thickness within a range ofabout 2.5 millimeters to about 35 millimeters.
 8. The process chamber ofclaim 1, wherein a support shaft coupled to the substrate support isdisposed through a center of an innermost ring of the plurality ofconcentric rings.
 9. The process chamber or claim 8, wherein the supportshaft is formed form quartz and contains a hollow cavity therein. 10.The process chamber of claim 1, wherein the light focusing assemblyfurther comprises a plurality of refractive elements disposed betweenadjacent concentric rings or polygonal approximations to rings.
 11. Theprocess chamber of claim 10, wherein the refractive elements includeconvex or concave lenses.
 12. The process chamber of claim 10, whereinthe refractive elements include Fresnel lenses.
 13. The process chamberof claim 1, wherein the lamps are positioned outside of a processingregion of the chamber body.
 14. A process chamber, comprising: a chamberbody including a dome that allows the transmission of radiant energytherethrough; a substrate support disposed within the chamber body, thesubstrate support having a support shaft extending therefrom; aplurality of lamps disposed adjacent to the dome; and a light focusingassembly positioned within the chamber body between the opticallytransparent dome and the substrate support, the light focusing assemblyin contact with an upper surface of the dome, the light focusingassembly comprising: a plurality of concentric rings or polygonalapproximations to rings having gaps therebetween, wherein the concentricrings or the polygonal approximations to rings include a reflectivecoating on sidewalls thereof adjacent the gaps; an upper plate disposedat a first end of the plurality of concentric rings or polygonalapproximations to rings; and a lower plate disposed at a second end ofthe plurality of concentric rings or polygonal approximations to rings.15. The process chamber of claim 14, wherein the support shaft includesa hollow cavity therein.
 16. The process chamber of claim 15, whereinthe light focusing assembly further comprises a plurality of refractiveelements disposed between adjacent concentric rings or polygonalapproximations to rings.
 17. The process chamber of claim 15, whereinthe refractive element comprises a concave lens.
 18. The process chamberof claim 15, wherein the refractive element comprises a convex lens. 19.The process chamber of claim 15, wherein the refractive elementcomprises a Fresnel lens.
 20. (canceled)
 21. A light focusing assembly,comprising: a plurality of concentric rings or polygonal approximationsto rings having gaps therebetween, wherein the concentric rings or thepolygonal approximations to rings include a reflective coating onsidewalls thereof adjacent the gaps; an upper plate disposed at a firstend of the plurality of concentric rings or polygonal approximations torings; and a lower plate disposed at a second end of the plurality ofconcentric rings or polygonal approximations to rings.